Learning and memory abilities decline with age; however collaborative learning with a familiar partner has been found to improve older adults’ performance on memory tasks and reduce these age-related differences. However it is unclear whether collaborating with a familiar partner is more beneficial to learning compared with collaborating with a stranger. Similarly, it is unclear whether older adults collaborate similarly with human and computer partners. The aim of this PhD thesis is to understand the role of collaborator identity on collaborative learning, and to investigate whether collaborative learning is as efficient and accurate with a range of learning partners. While collaborative learning is a socially-based memory task, the relationships between collaborative learning and social cognition have not yet been explored. The secondary aim of this thesis is to use experimental collaborative learning paradigms alongside standardised and experimental measures of social cognition to explore whether social cognition accounts for a significant amount of variance in collaborative learning performance with different partners. Two studies compare younger and older adults’ learning with familiar and unfamiliar partners on different collaborative learning paradigms. Two subsequent studies compare older adults’ learning on computerised versions of the collaborative learning tasks with partners they perceive to be humans or computers based on recordings of natural human or synthetic speech respectively. In all studies, measures of social cognition were used to assess whether social abilities affect learning outcomes with different partner types. When comparing older and younger adults’ results, familiarity had no effect on learning or immediate or delayed recall performance. Older adults initially took longer to complete the learning trials but performed with similar efficiency as younger adults by the final trials. Younger and older adults recalled collaboratively learned information with comparable accuracy after a delay of one hour, however after one week, older adults recalled the route less accurately than younger adults. Social cognition was not related to collaborative learning with familiar partners, but was related with unfamiliar partners, suggesting that those who are better able to take the perspective of another person may benefit during interactive learning. Social cognition was related to collaborative learning with perceived human partners but not perceived computer partners. This thesis offers a new perspective on the interplay between social and cognitive function in collaborative learning with different learning partners, and explores the differences between younger and older adults when learning collaboratively. The findings are discussed in relation to cognitive, social, and technological theories. On the whole, collaborative learning can result in older adults learning with similar speed and accuracy to younger adults; while familiarity does not improve learning outcomes, perceived human-ness does.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Colleen Kelley, Florida State University, College of Arts and Sciences, Dept. of Psychology. Title and description from dissertation home page (viewed Jan. 13, 2005). Includes bibliographical references.

The role of the primate frontopolar cortex (FPC) has been investigated using human neuroimaging, lesion and disruption techniques. The results of these investigations have led to a variety of theories regarding the function of this region. It has been linked to the formation of task sets, the performance of multiple tasks, reasoning, context-specific memory (including episodic memory, prospective memory and source memory), attention to internally or externally generated information, mentalising and decision-making. It has not previously been possible to study this area using animal lesion techniques. Here, behavioural experiments conducted using non-human primates (rhesus macaque monkeys) who have received lesions to the frontal pole investigate the contribution of this region to context-specific memory, decision-making and social cognition. Functional magnetic resonance imaging (fMRI) is used to investigate changes in functional network connectivity which occur after lesions to this region. A long-lasting impairment is observed in contextual memory judgements (specifically, how recently a stimulus was encountered) after lesions to the frontal pole. An analysis of the influence of the outcomes of previous choices on behaviour on an analogue to the Wisconsin Card Sorting Test (WCST) indicate that monkeys with lesions to area 10 may be less influenced by the outcomes of an extended history of rewards than control animals. Long-lasting widespread disruption to functional networks after lesions to this region indicate that indirect anatomical connections from this region to posterior areas play a crucial role in the normal functioning of posterior networks.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Psychology, Behavioral Neuroscience, 2008. / Includes bibliographical references.

Thesis (M.A.)--State University of New York at Binghamton, Department of Psychology, 2005. / Includes bibliographical references.

This thesis is concerned with the age-related changes in working memory (WM), and the inter-individual differences in cognitive and neural mechanisms that correspond to healthy versus poor ageing of WM function. The first half of this thesis focusses on the age-related decline in WM and whether preserved top-down attentional control could mitigate such deficits. In Chapter 2, I present a functional MRI study showing that older adults reliably recruit brain networks that subserve cognitive control, which work in concert with the task relevant sensory areas during effective selective WM. In Chapter 3, I show that older adults retain flexible control over WM representations, and this ability corresponded to the reliable recruitment of neural signals of orienting attention qualitatively similar to those observed in younger adults. Magnetoencephalographic recordings showed that the neural dynamics during orienting attention within WM was predictive of good performance, demonstrating that the more efficient the process of orienting within WM to select the target item, the better the memory representation can be preserved for upcoming behaviour. In the second half of this thesis, I explored whether WM for affective content has a special status in healthy ageing. In Chapter 4, I developed an emotional WM precision task to measure WM abilities for emotional content appropriate for elderly adults. In Chapter 5, I tested a group of young and older adults on WM and perceptual-matching abilities for emotional faces. The results suggest that older adults show a general impairment in task performance, but possibly with some preservation in the ability to maintain emotional content in WM. There were marked differences in how the emotional information was processed between age groups, in which older adults have a tendency to represent negative stimuli as less negative than younger adults in perception and WM, and tended to show a positive interpretation of the valence of more ambiguous emotional stimuli. In Chapter 6, I summarise the findings presented in this thesis, discuss the implications of the key findings, and consider some suggestions for future studies that aim to elucidate the mechanisms of WM in healthy ageing.

The hippocampal formation has been implicated in spatial formation for many decades. The hippocampus proper has received the most attention but other regions of the hippocampal formation contribute largely to spatial cognition. This thesis concentrated on one such region, the postsubiculum. The postsubiculum is considered important because it contains head direction cells and because it thought to be a major input to the hippocampus, via the entorhinal cortex. This thesis aims to test the functional role of the rat postsubiculum under two types of situation: one where the rat must rely on idiothetic cues for navigation, and another where the rat has visual cues present and can rely on these for orientation. The thesis also investigates hippocampal place cells and their stability over time after short exposures to novel environments. Chapter 3 of this thesis aimed to test whether the postsubiculum is necessary for path integration during a homing task. Rats were trained on a homing task on a circular platform maze. Once the task was acquired, rats were given lesions of the postsubiculum or sham lesions and then re-tested on the path integration task. The homing performance of rats with lesions of the postsubiculum was as good as that of the sham rats. A series of manipulations suggests that the rats were homing by path integration, confirmed by probe tests. The rats were then tested on a forced-choice delayed alternation T-maze task that revealed a significant impairment in alternation with delays of 5, 30, and 60 seconds. This suggests that the postsubiculum is not necessary for path integration in a homing task but is necessary for avoiding previously visited locations as is necessary in an alternation task. The experiments in Chapters 4 and 5 of this thesis aimed to investigate the effects of postsubiculum pharmacological inactivation on hippocampal CA1 place cells when rats were introduced to a novel environment with visual cues. A necessary first step was to assess place cells without any manipulation of the postsubiculum (Chapter 4) and then use information gained from this in the design of experiments in Chapter 5. Rats chronically implanted with recording electrodes in the CA1 region of the hippocampus were exposed to novel cue-rich environments whilst place fields were recorded. Following delays of 3, 6, or 24 hours, the same cells were recorded again in the same environment but with the cues rotated by 90°. Pixel-by-pixel correlations of the place fields show that stability of the place fields was significantly lower at 24 hours than at 3 hours. Stability after 6 hours was not significantly different from 3 hours. In the third set of experiments, rats were implanted with drug infusion cannulae in the postsubiculum and recording electrodes in CA1. Following infusions of either the AMPA receptor antagonist CXQX, the NMDA receptor antagonist D-AP5 or a control infusion of ACSF, place field stability was assessed as rats were exposed to a cylindrical environment with a single polarising cue card for 3 x 10 minute sessions and then again 6 hours later. There were no differences in place field correlations between the 3 drug conditions, although there was evidence of larger changes in spatial information content between cells in the CNQX and AP5 drug condition, but not the ACSF condition. The results suggest that, under the present testing conditions, place fields stability did not depend upon AMPA receptor-mediated transmission nor did it depend on NMDA receptor-mediated synaptic plasticity.

Abstract This study examined memory functioning from a female perspective, with the aim of determining factors that might impact performance and render the accuracy of memory measurement, particularly with advancing age, problematic. Factors investigated, among others, were the role of attention and/or engagement with the memory tasks administered, state affect (i.e., positive and negative arousal) at time of testing, subjective memory appraisal, particularly in the domain of perceived memory self-efficacy (MSE), and the use of hormone replacement therapy (HRT) by older post-menopausal women. Two experimental computer-based tests of episodic memory, Paired Associates (PA) and Serial Recall (SR), were administered to 181 female participants aged 18 to 86 years. The tasks were designed to emphasise components that make episodic memory especially difficult, and minimise the use of strategies that might assist recall. Thus, they varied the requirement for recall as opposed to recognition, the need to form an association between a pair of unrelated words, and the need to discriminate the most recent list from earlier list(s). Other measures used included a demographic survey administered to participants individually in an interview format, and a number of variables examined in this study derived from responses to items contained in this survey. The research battery also included psychometric measures of transient affective states, psychological well-being, alertness, in addition to measures of global cognitive status and metamemory (i.e., subjective memory appraisal). The overall aim was to examine a range of factors that might influence episodic memory performance in cognitively intact healthy women, and thus render the interpretation of age-related changes to memory functioning problematic. For analyses participants were assigned to three groups - young, middle-aged and older. There were 60 young adults aged 18 to 29 years, 60 middle-aged adults aged 49 to 60 years, and 61 older adults aged 61 to 86 years. Each participant was tested individually in a single session lasting approximately 3 ½ hours, with younger participants requiring less time to complete assessments. Order of test administration and instructions were standardised across the entire sample. Inferential statistics included correlation, t-test statistic, and analysis of variance (ANOVA) with Tukey post-hoc comparisons. Hierarchical multiple regression analyses were conducted to determine key correlates of memory performance outcomes. No significant differences between the cohorts were found in mean years of education. However, episodic memory recall differed significantly by age group. As expected, young adults recalled significantly more words in the memory tasks than their older counterparts, and middle-aged adults outperformed adults in the oldest cohort. Moreover, older adults’ performance deficits were more pronounced in the tasks requiring that they make an association between a pair of unrelated words. Across all cases, transient mood states were significantly related to memory scores; however, individuals in the oldest cohort were particularly vulnerable to mood fluctuations. This cohort experienced a significantly greater decline in positive affect and a significant greater increase in negative affect while undergoing memory testing, highlighting their greater vulnerability to stressors inherent in a memory testing situation. Although scores on the measure of attention were near ceiling, indicative of participants’ level of effort, motivation, and engagement with the memory tasks, the measure of attention discriminated between older and younger adults’ results, and was a key predictor of memory performance. Noteworthy is that attention scores significantly contributed to performance variability in younger and older adults but not in middle-aged adults. Across all cases, age, education, and attention were the key contributing factors to variability in memory scores. Although four lifestyle factors: (1) subjective sleep appraisal, (2) body mass index (BMI), (3) physical activity, and (4) caffeine intake were significantly associated with performance in the memory tasks, once the effects of these key variables were removed, lifestyle factor did not uniquely contribute to performance variability. Moreover, no association was found between hormone replacement therapy (HRT) and episodic memory performance across the broader sample. However, in a small subgroup of older women (n = 15, M age = 66 years), long-term users of this treatment, HRT had a significant effect on memory performance and was indicative of better recall on the memory tasks. The effect of subjective memory appraisal, MSE included, on objective performance outcomes was examined. The results showed that memory self-evaluations were not a significant contributing factor to episodic memory performance, confirming that memory self-appraisal is a poor predictor of actual memory performance, and thus does not pose a challenge to the measurement of age-related changes to memory abilities. Although there were commonalities, factors influencing memory performance differed by age cohort. For example, in young adults, positive mood, a perception of sleeping well, subjective health, and attention were significantly related to performance on the memory tasks. However, once the effect of attention was removed in the regression analysis, no other variable was predictive of episodic memory functioning in this cohort. In contrast, the single significant predictor of memory performance in middle-aged individuals was education, and neither attention, nor positive mood, or physical activity had a significant effect on this cohort’s performance. Similarly, having more years of formal education benefited older adults’ episodic memory functioning. However, high scores on global cognitive functioning and on the tasks measuring attention were equally important to episodic memory recall in this age group. In sum, the significant contribution of age to memory variability attested to the utility of the memory measures in detecting age-related changes to episodic memory functioning, which were independent of deficits in attention or level of education. Moreover, the effect of several factors (e.g., transient mood, lifestyle) on memory scores was explained by an effect on attention, and this has clear implication for the proper evaluation of long-term changes to memory functioning. Limitations of the study and suggestion for future research are discussed.

Abstract This study examined memory functioning from a female perspective, with the aim of determining factors that might impact performance and render the accuracy of memory measurement, particularly with advancing age, problematic. Factors investigated, among others, were the role of attention and/or engagement with the memory tasks administered, state affect (i.e., positive and negative arousal) at time of testing, subjective memory appraisal, particularly in the domain of perceived memory self-efficacy (MSE), and the use of hormone replacement therapy (HRT) by older post-menopausal women. Two experimental computer-based tests of episodic memory, Paired Associates (PA) and Serial Recall (SR), were administered to 181 female participants aged 18 to 86 years. The tasks were designed to emphasise components that make episodic memory especially difficult, and minimise the use of strategies that might assist recall. Thus, they varied the requirement for recall as opposed to recognition, the need to form an association between a pair of unrelated words, and the need to discriminate the most recent list from earlier list(s). Other measures used included a demographic survey administered to participants individually in an interview format, and a number of variables examined in this study derived from responses to items contained in this survey. The research battery also included psychometric measures of transient affective states, psychological well-being, alertness, in addition to measures of global cognitive status and metamemory (i.e., subjective memory appraisal). The overall aim was to examine a range of factors that might influence episodic memory performance in cognitively intact healthy women, and thus render the interpretation of age-related changes to memory functioning problematic. For analyses participants were assigned to three groups - young, middle-aged and older. There were 60 young adults aged 18 to 29 years, 60 middle-aged adults aged 49 to 60 years, and 61 older adults aged 61 to 86 years. Each participant was tested individually in a single session lasting approximately 3 ½ hours, with younger participants requiring less time to complete assessments. Order of test administration and instructions were standardised across the entire sample. Inferential statistics included correlation, t-test statistic, and analysis of variance (ANOVA) with Tukey post-hoc comparisons. Hierarchical multiple regression analyses were conducted to determine key correlates of memory performance outcomes. No significant differences between the cohorts were found in mean years of education. However, episodic memory recall differed significantly by age group. As expected, young adults recalled significantly more words in the memory tasks than their older counterparts, and middle-aged adults outperformed adults in the oldest cohort. Moreover, older adults’ performance deficits were more pronounced in the tasks requiring that they make an association between a pair of unrelated words. Across all cases, transient mood states were significantly related to memory scores; however, individuals in the oldest cohort were particularly vulnerable to mood fluctuations. This cohort experienced a significantly greater decline in positive affect and a significant greater increase in negative affect while undergoing memory testing, highlighting their greater vulnerability to stressors inherent in a memory testing situation. Although scores on the measure of attention were near ceiling, indicative of participants’ level of effort, motivation, and engagement with the memory tasks, the measure of attention discriminated between older and younger adults’ results, and was a key predictor of memory performance. Noteworthy is that attention scores significantly contributed to performance variability in younger and older adults but not in middle-aged adults. Across all cases, age, education, and attention were the key contributing factors to variability in memory scores. Although four lifestyle factors: (1) subjective sleep appraisal, (2) body mass index (BMI), (3) physical activity, and (4) caffeine intake were significantly associated with performance in the memory tasks, once the effects of these key variables were removed, lifestyle factor did not uniquely contribute to performance variability. Moreover, no association was found between hormone replacement therapy (HRT) and episodic memory performance across the broader sample. However, in a small subgroup of older women (n = 15, M age = 66 years), long-term users of this treatment, HRT had a significant effect on memory performance and was indicative of better recall on the memory tasks. The effect of subjective memory appraisal, MSE included, on objective performance outcomes was examined. The results showed that memory self-evaluations were not a significant contributing factor to episodic memory performance, confirming that memory self-appraisal is a poor predictor of actual memory performance, and thus does not pose a challenge to the measurement of age-related changes to memory abilities. Although there were commonalities, factors influencing memory performance differed by age cohort. For example, in young adults, positive mood, a perception of sleeping well, subjective health, and attention were significantly related to performance on the memory tasks. However, once the effect of attention was removed in the regression analysis, no other variable was predictive of episodic memory functioning in this cohort. In contrast, the single significant predictor of memory performance in middle-aged individuals was education, and neither attention, nor positive mood, or physical activity had a significant effect on this cohort’s performance. Similarly, having more years of formal education benefited older adults’ episodic memory functioning. However, high scores on global cognitive functioning and on the tasks measuring attention were equally important to episodic memory recall in this age group. In sum, the significant contribution of age to memory variability attested to the utility of the memory measures in detecting age-related changes to episodic memory functioning, which were independent of deficits in attention or level of education. Moreover, the effect of several factors (e.g., transient mood, lifestyle) on memory scores was explained by an effect on attention, and this has clear implication for the proper evaluation of long-term changes to memory functioning. Limitations of the study and suggestion for future research are discussed.

<p>Cilj rada: Posmatrano je da li postoji povezanost kliničkih parametara, bihejvioralnih simptoma i postignuća na testovima kognitivnih funkcija sa karakteristikama hoda kod obolelih od Parkinsonove bolesti. Analizirana je i povezanost nalaza hiperehogenosti strukture substantia nigra dobijenog transkranijalnim parenhimskim ultrazvukom sa karakteristikama hoda.Materijal I metode: Istraživanjem je obuhvaćeno 60 obolelih od Parkinsonove bolesti (22 žene i 38 mu&scaron;karaca, sa trajanjem bolesti 5,06&plusmn;4,54 godina, ukupnim UPDRS 39,76&plusmn;36,65, UPDRS III 24,28&plusmn;15,18) koji su prema stadijumu bolesti po Hen i Jarovoj skali (H&amp;Y) podeljeni u tri podgrupe sa po 20 ispitanika: H&amp;Y 1, 2 i 3. Kontrolnu grupu činilo je 35 zdravih ispitanika (19 žena i 16 mu&scaron;karaca) koji se od grupe obolelih nisu razlikovali u pogledu godina starosti (oboleli 64,21&plusmn;6,92 godina, zdravi 63,45&plusmn;7,75, p=0,832) i godina obrazovanja (oboleli 12,63&plusmn;3,16 godina, zdravi 12,57&plusmn;2,87, p=0,954). Iz analize su isključeni ispitanici čiji je skor MMSE bio manji od 24. Procena težine motornih znakova Parkinsonove bolesti vr&scaron;ena je Unifikovanom skalom za kvantifikovanje Parkinsonove bolesti, treći deo (UPDRS III). Za globalnu procenu kognicije je kori&scaron;ćena Revidirana Adenbrukova kogntivna skala (ACE- R), a za procenu egzekutivnih funkcija su kori&scaron;ćeni baterija za procenu frontalnih funkcija (FAB) i Egzekutivni intervju (EXIT-25). Za evaluaciju depresije kori&scaron;ćene su Hamiltonova skala za procenu depresije (HAM- D) i Bekova skala depresivnosti (BDI II), za procenu anksioznosti Hamiltonova skala za procenu anksioznosti (HAM- A), a za procenu apatije Skala apatije (AS).Određivanje vremenskih i prostornih parametara hoda vr&scaron;eno je pomoću GAITRite sistema, tokom &bdquo;on&rdquo; perioda. Analizirano je osam parametara hoda: vreme dvokoraka (CT), dužina dvokoraka (SL), vreme zamaha (ST) i vreme dvostrukog oslonca (DS), kao i njihovi koeficijenti varijacija (CV). Posmatran je i uticaj dvostrukog zadatka na parametre hoda. Kao dodatni zadatak tokom hoda primenjen je kognitivni zadatak (oduzima -7 tokom hoda), motorni zadatak (nosi ča&scaron;u punu vode) i kombinovani zadatak (oduzima i nosi ča&scaron;u istovremeno). Veličina hiperehogenosti substantia nigra merena je transkranijalnim parenhimskim ultrazvukom. Rezultati: U poređenju sa zdravim vr&scaron;njacima, oboleli od Parkinsonove bolesti imali su značajno izraženiji varijabilitet koraka pri hodu bez zadatka (skraćen SL, povećan CVSL i CVCT, varijabilitet koraka bio je jo&scaron; izraženiji, dok je pri motornom zadatku postojala i značajna razlika DS i CVDS (p&lt;0,05), tj. parametara kojima se izražava ravnoteža koraka. U uslovima kombinovanog zadatka ove razlike su se potencirale. Parametri hoda (SL, VCSL, CVCT I CVST) minimalno su se razlikovali kod obolelih u najranijim stadijumima bolesti (H&amp;Y 1) u odnosu na zdrave, dok su razlike postajale izraženije kako je bolest bila u odmaklijim stadijumima (H&amp;Y 2 I H&amp;Y 3). U grupi zdravih starost ispitanika korelirala je sa varijabilitetom koraka jedino u uslovima dvostrukog zadatka. Kod obolelih ova povezanost je uočena i pri hodu bez zadatka, a povezanost je bila jača u uslovima dvostrukog zadatka. Starost ispitanika i težina motornih znakova na UPDRS III korelirali su sa parametrima hoda kod obolelih od PB. Skorovi apatije i depresivnosti korelirali su sa promenama parametara hoda kod obolelih, s tim &scaron;to je apatija bila prisutna već u najranijim, a depresija tek u kasnijim stadijumima bolesti. Niža postignuća na testovima egzekutivnih funkcija povezana su sa pogor&scaron;anjem svih parametara hoda. Sa pogor&scaron;anjem parametara hoda tokom trajanja bolesti koreliraju i niža postignuća na testovima jezičkih i vidno- prostornih funkcija, kao i deficit pamćenja. Veličina hiperehogenosti korelira sa CV svih parametara hoda. Zaključak: Kod obolelih od Parkinsonove bolesti značajno se razlikuju vremenski i prostorni parametri hoda u poređenju sa zdravim, pre svega oni kojima se opisuje varijabilitet koraka. Ovi parametri su izraženiji kada se tokom hoda obavlja i dodatni kognitivni zadatak. Kada se tokom hoda obavlja motorni ili kombinovani motorni i kognitivni zadatak, pored varijabiliteta koraka javlja se i značajno produžen DS koji ukazuje na poremećaj ravnoteže. Na parametre hoda utiču starost ispitanika, težina i stadijum Parkinsonove bolesti. Apatija i depresija takođe značajno utiču na parametre hoda kod obolelih. Apatija se javlja u najranijim, a depresivnost tek u kasnijim stadijumima bolesti, &scaron;to govori u prilog stanovi&scaron;ta da je apatija zaseban simptom bolesti povezan sa dopaminergičkom disfunkcijom. Pogor&scaron;anja parametara hoda koreliraju sa o&scaron;tećenjem kognitivnih funkcija, pre svega egzekutivnih. U odmaklim stadijumima bolesti sa pogor&scaron;anjem hoda povezana su i lo&scaron;ija postignuća na testovima vidno-prostornih funkcija i pamćenja. Hiperehogenost substantia nigra na transkranijalnom parenhimskom ultrazvuku, koja se značajno če&scaron;će javlja i značajno je veće povr&scaron;ine kod obolelih u odnosu na zdrave, korelira sa varijabilitetom koraka.</p> / <p>Objectives: The aim of the study was to assess the contribution of clinical presentation, behavioral symptoms and cognitive functioning to gait characteristics in Parkinson&rsquo;s disease (PD). Hyperechogenicity of the substantia nigra on transcranial parenchimal ultrasound and its correlations with gait characteristics was also analyzed. Material and Methods: The experimental group consisted of 60 patients suffering from Parkinson&rsquo;s disease (22 women and 38 men, disease duration 5.06&plusmn;4.54, Unified Parkinson&#39;s Disease Rating Scale (UPDRS) total 39.76&plusmn;36.65, and UPDRS III 24.28&plusmn;15.18), who were classified into three subgroups according to the Hoehn and Yahr (H&amp;Y) stage of the disease: H&amp;Y 1, H&amp;Y 2 and H&amp;Y 3, with each subgroup containing 20 patients. The control group included 35 healthy subjects (19 women and 16 men) who were matched for years of age (64.21&plusmn;6.92 years PD vs 63.45&plusmn;7.75 healthy; p= .832) and formal education (12.63&plusmn;3.16 years PD vs 12.57&plusmn;2.87 healthy, p= .954). The subjects with MMSE&lt;24 were concerned demented and excluded from further analysis. The disease severity was assessed by the UPDRS, motor part (UPDRS III). Addenbrooke&rsquo;s Cognitive Examination-Revised (ACE-R) was used in assessment of global cognition, while executive functions were examined by Frontal Assessment Battery (FAB) and Executive Interview (EXIT-25) Hamilton&rsquo;s Depression Rating Scale (HAM-D) and Beck&rsquo;s Depression Inventory (BDI II) were used to screen for symptoms of depression, and the Apathy Scale (AS) and Hamilton&rsquo;s Anxiety Rating Scale (HAM- A) were used to assess apathy and anxiety. The measurements of spatial and temporal parameters of gait were performed using the GAITRite system, during the &ldquo;on&rdquo; state. The following eight parameters were analyzed: Cycle Time (CT), Stride Length (SL), Swing Time (ST) and Double Support Time (DS), as well as their coefficients of variation (CV). The impact of dual task on gait parameters was also observed. The subjects were asked to walk and simultaneously perform cognitive task (subtracting -7), then motor task (carrying a glass of water) and eventually combined task (subtracting and carrying a glass of water), while walking on the GAITRite electronic pathway. Transcranial parenchymal ultrasound was used to measure hyperechogenicity of substantia nigra. Results: Compared to healthy controls, PD patients had significantly higher gait variability during gait without additional tasks (decreased SL, increased CVSL and CVCT; p&lt; .05), whereas with a cognitive task the variability was even higher. During the motor task DS and CVDS were significantly increased as well, implying gait instability. A combined task had similar effects as the motor task, affecting all parameters. When the experimental group was divided into subgroups, variability of gait (SL, VCSL, CVCTandCVST) was minor in subgroup H&amp;Y 1, but more pronounced in later stages (H&amp;Y 2 and H&amp;Y 3). The age correlated with gait variability (CVCT and CVSL) only during the dual task in healthy subjects, whereas in PD patients the association was significant during normal gait and increased on the dual task. The age and severity of the disease on the UPDRS III also correlated with gait parameters. Apathy and depression were also associated with gait variability. Symptoms of apathy were significant in the earliest stages (H&amp;Y 1), whereas depression was notable in the later stages (H&amp;Y 3). Worse scores on tests of executive functions correlated with impairment of gait parameters. The impact of diminished language, visuo-spatial and memory functions on gait was also significant. Hyperechogenicity of the substantia nigra on transcranial parenchymal ultrasound occurred more frequently and was larger in PD patients and correlated well with gait variability. Conclusion: There is a significant impairment of temporal and spatial gait parameters in PD patients compared to healthy subjects, particularly the parameters of gait variability. These parameters become even more impaired during a simultaneous cognitive task. When a motor or combined task is performed, there is additional increase of DS, implying impairment of stability. Also, age and disease severity affect gait in PD patients. Apathy is significant in early stages (H&amp;Y 1) and depression in later stages (H&amp;Y 3), the finding which may be explained by the dopaminergic origin of apathy. Impairment of cognitive functions, most importantly executive dysfunction, are also associated with gait variability. Lower scores at visuo-spatial, language and memory tests are associated with worsened gait parameters of gait in later stages of PD. Finally, hyperechogenicity of the substantia nigra on transcranial parenchymal sonography, which occurs more frequently and is larger in PD patients, correlates with gait variability.</p>